Sen. John McCain takes to the Senate floor to defend Huma Abedin, a top aide to Secretary of State Hillary Clinton whom GOP lawmakers have accused of having ties to the pan-Arab Muslim Brotherhood.

“These attacks on Huma have no logic, no basis and no merit. And they… (Alex Wong, Getty Images )

WASHINGTON — Sen. John McCain (R-Ariz.) came to an unexpected and impassioned defense of Huma Abedin, a top aide to Secretary of State Hillary Rodham Clinton, saying that "sinister accusations" by congressional conservatives about her alleged connection to the Muslim Brotherhood must end.

The attacks have been led by Rep. Michele Bachmann (R-Minn.), the chairwoman of the tea party caucus in the House, and four other lawmakers, who have asked federal officials to investigate whether Abedin, a Muslim American who is deputy chief of staff at the State Department, is influencing U.S. policy in ways beneficial to the pan-Arab Islamic group.

Abedin is one of Clinton's closest aides, and former President Clinton presided at her wedding. The lawmakers cite an online report that alleges Abedin's relatives, including her deceased father, have connections to the Muslim Brotherhood.

"These attacks on Huma have no logic, no basis and no merit. And they need to stop now," said McCain, the 2008 Republican presidential nominee and its top voice on defense policy. "I have every confidence in Huma's loyalty to our country, and everyone else should as well. All Americans owe Huma a debt of gratitude for her many years of superior public service. I hope these ugly and unfortunate attacks on her can be immediately brought to an end and put behind us before any further damage is done to a woman, an American, of genuine patriotism and love of country."

McCain acknowledged the unusual nature of his decision to come to the Senate floor to speak about a particular individual. But he said he was compelled to do so to protect her character and reputation in the face of attacks being made "without concern for fact or fairness."

"Huma represents what is best about America: the daughter of immigrants, who has risen to the highest levels of our government on the basis of her substantial personal merit and her abiding commitment to the American ideals that she embodies so fully," said McCain, who said he had seen Abedin in action overseas, at Clinton's side. "I am proud to know Huma, and to call her my friend."

Bachmann and the other lawmakers singled out various individuals for scrutiny in a series of letters late last week to the inspectors general at several departments, including State, Defense and Homeland Security. They are seeking investigations into the alleged ties of these individuals, who work for or advise the agencies, to the Muslim Brotherhood.

"We seek answers through these letters because we will not tolerate this group and its affiliates holding positions of power in our government or influencing our nation's leaders," Bachmann said in a statement accompanying the letters signed by Reps. Louie Gohmert (R-Texas), Trent Franks (R-Ariz.), Tom Rooney (R-Fla.) and Lynn Westmoreland (R-Ga.).

Bachmann did not back down Wednesday after the rebuke from McCain. She said the letters were "unfortunately being distorted."

"The intention of the letters was to outline the serious national security concerns I had and ask for answers to questions regarding the Muslim Brotherhood and other radical groups' access to top Obama administration officials," Bachmann said in a statement. She said she would not be "silent."

The congresswoman drew on the report "The Muslim Brotherhood in America: The Enemy from Within," an online video project from the Center for Security Policy. The group's founder and president, Frank Gaffney, is a former Reagan administration defense official who hosts the nationally syndicated "Secure Freedom Radio" show.

The Muslim Brotherhood's candidate, Mohamed Morsi, recently won the presidential election in Egypt, besting the military-backed candidate in the aftermath of the "Arab Spring"uprising that toppled longtime U.S. ally Hosni Mubarak. Clinton met with Morsi last week in Cairo.

As one of Clinton's top aides, Abedin has long been a quiet presence — on Clinton's Senate staff and later on the campaign trail as the former first lady sought the 2008 Democratic nomination for president. She became more known to Americans after former President Clinton officiated at her 2010 wedding to then-Rep. Anthony Weiner (D-N.Y.), who resigned in 2011 after it was disclosed he sent sexually suggestive text messages to several women who connected with him on social networking sites.

Abedin gave birth to the couple's first child, a son, later last year.